Embodiments relate to photo cell devices. In one embodiment, a trench-based photo cells provides very fast capture of photo-generated charge carriers, particularly when compared with conventional approaches, as the trenches of the photo cells create depleted regions deep within the bulk of the substrate that avoid the time-consuming diffusion of carriers.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A photo cell comprising: a substrate; and at least two vertical trenches formed in the substrate and laterally spaced apart from one another such that a doping type of a bulk of the substrate around and between the at least two vertical trenches is the same, wherein when the photo cell operates in a depletion mode a space charge region extends laterally in the substrate with a first trench of the at least two vertical trenches disposed in the space charge region and a second trench of the at least two vertical trenches disposed in a neutral region of the substrate, wherein a depth of the at least two trenches is related to a wavelength of a signal source.
2. The photo cell of claim 1 , wherein the at least two vertical trenches extend at least about 5 microns into the substrate.
3. The photo cell of claim 2 , wherein the at least two vertical trenches extend at least about 30 microns into the substrate.
4. The photo cell of claim 3 , wherein a width of each of the at least two vertical trenches is about 0.1 microns to about 5 microns, and where a length of each of the at least two vertical trenches is about 0.1 microns to about 100 microns.
5. The photo cell of claim 1 , wherein the space charge region is formed within the neutral region.
6. A photo cell comprising: a substrate; and at least two vertical trenches formed in the substrate and laterally spaced apart from one another such that a doping type of a bulk of the substrate around and between the at least two vertical trenches is the same, wherein when the photo cell operates in a depletion mode a space charge region extends laterally in the substrate with a first trench of the at least two vertical trenches disposed in the space charge region and a second trench of the at least two vertical trenches disposed in a neutral region of the substrate, where a lateral distance separating the at least two vertical trenches is related to a doping level of the substrate such that upon operation a biasing of one of the at least two vertical trenches results in formation of a fully depleted gap between the at least two verticle trenches.
7. The photo cell of claim 6 , wherein the lateral distance separating the at least two vertical trenches is in a range of about 0.5 microns to about 100 microns.
8. The photo cell of claim 1 , further comprising at least two electrodes, a first electrode coupled to the first trench and a second electrode coupled to the second trench.
9. The photo cell of claim 8 , wherein the electrodes are configured to be biased alternately with a positive voltage.
10. The photo cell of claim 8 , further comprising circuitry coupled to the electrodes and configured to compare a charge at the first electrode with a charge at the second electrode.
11. The photo cell of claim 1 , wherein the first trench is substantially parallel to the second trenches.
12. A photo cell comprising; a substrate; at least two vertical trenches formed in the substrate and laterally spaced apart from one another such that a doping type of a bulk of the substrate around and between the at least two vertical trenches is the same, wherein when the photo cell operates in a depletion mode a space charge region extends laterally in the substrate with a first trench of the at least two vertical trenches disposed in the space charge region and a second trench of the at least two vertical trenches disposed in a neutral region of the substrate: and a third trench and a fourth trench formed in the substrate.
13. The photo cell of claim 12 , wherein the first and second trenches are substantially parallel with one another in a first pair, the third and fourth trenches are substantially parallel with another in a second pair, and the first and second pairs are substantially perpendicular with one another.
14. The photo cell of claim 13 , wherein the first and second pairs are configured to receive, alternately by the first pair and the second pair, a bias voltage.
15. The photo cell of claim 1 , wherein the first trench is disposed in the space charge region when a positive voltage is applied to the first trench and the substrate comprises a p-substrate.
16. The photo cell of claim 1 , wherein the first trench, is disposed in the space charge region when a negative voltage is applied to the first trench and the substrate comprises an n-substrate.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
December 21, 2011
November 17, 2015
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